Intrinsic viscosity-number average molecular weight relationship for poly (n-Octadecyl acrylate) and poly (N-n-octadecylacrylamide)

Intrinsic viscosity-number average molecular weight relationships have been measured, at 30C in benzene, for poly (n-octadecyl acrylate) as [η]=2.72×10⁻⁴ Mn^0.638 and for poly (N-n-octadecylacrylamide) as [η]=0.82×10⁻⁴ Mn^0.676. Whole polymers of various molecular weights were prepared in benzene solution at 65C with dodecyl mercaptan as primary regulator. By the use of these parameters, the molecular weight of such polymers and their homologs may now be measured by simple solution-viscosity determinations. In the expression { } (relating degrees of polymerization { } to the mercaptan/monomer ratio), intercept { } and apparent transfer constant C_s for n-octadecyl acrylate were 6.28×10⁻³ and 0.68; for N-n-octadecylacrylamide 1.10×10⁻³ and 0.62 respectively. These parameters permit preparation of homopolymers of chosen molecular weight. Presented at the AOCS Meeting, Philadelphia, October 1966 E. Utiliz. Res. Devel. Div., ARS, USDA.